Green preparation of water-stable coptidis-dyeing composite nanofiber filters with ultraviolet shielding and antibacterial activity and biodegradability

Particulate matter pollution and bacteria in the air have become hot topics due to their serious transmissibility and harm. Personal protection with respiratory masks was essential for our daily lives, but the reliability of commercial masks was limited by environmental factors, bacteria contamination, and non-degradability. Here, we prepared coptidis-dyeing polyvinyl alcohol (PVA)/polyacrylic acid (PAA) composite nanofiber filters with ultraviolet (UV) shielding, antibacterial activity, and biodegradability. The water stability of membranes was controlled using a green electrospinning-heat treatment process, improving the durability of masks in high humidity. The functionalization of composite nanofiber membranes was given through different coptidis-dyeing methods for the first time. The dyed membranes could maintain filtration efficiency of above 98 % against various NaCl particles (diameter of 0.225–7.25 μm) with a pressure drop of 196 Pa under a test flow rate of 32 L/min. Even at 85 L/min, the membrane could also maintain an interception efficiency of over 95 %, while the air resistance was below 343.2 Pa, meeting the requirements of GB 19083-2010 medical protective mask technology. Due to the natural functional properties of coptidis, the dyed membranes exhibited excellent antibacterial activity against Staphylococcus aureus of 99.8 % and a good UV protection index (UPF) of 286, respectively. The multifunctional dyed membranes are expected to become a filter layer that replaces the traditional melt-blown layer, providing insights to advance personal protective equipment.